Interactive calculator: do you win or lose with the new BMI?

Researchers at Oxford University have updated the body mass index with a new
formula that they say more accurately estimates body fat. Use the
interactive tool to see how your BMI is different under their proposal for a
new system.

According to Mr Trefethen, the current formula to calculate the score (weight/height2) is incorrect because "it divides the weight by too large a number for short people, and too small a number for tall people. So short people are misled into thinking they are thinner than they are, and tall people are misled into thinking they are fatter than they are."

His new formula (1.3 x weight/height2.5) is a better approximation of reality, because it scales more accurately as a person grows in height.

The result of the change is that shorter people under five feet might gain a BMI point, while taller individuals over six foot could lose one.

Dr Trefethen suggests that the reason the old formula has lasted so long is because when Quetelet invented the BMI, there were no calculators or computers so it was better to have a formula that was easy to calculate, than a complex one that no-one would use.